Device for the conical tapering of elongated workpieces having a circular cross section

ABSTRACT

A device for the conical tapering of a continuously rotating elongated workpiece having a circular cross section which is rotatable about the longitudinal axis thereof. At least two tools which can be fed radially are simultaneously advanced in axial direction and are arranged in one plane at a right angle to the workpiece axis. Each of the tools consists of two nonmovably connected working surfaces which define an angle with the infeed direction of the tools. On both tools the working surface which is the leading surface into each of the tools in the direction of rotation of the workpiece is longer than the other working surface and same is at most so long that when the tools are completely moved forwardly against one another the shorter working surface of each tool abuts with its front or leading side the longer working surface of the respectively other tool.

United States Patent [1 1 Thamasett DEVICE FOR THE CONICAL TAPERING OF ELONGATED WORKPIECES HAVING A CIRCULAR CROSS SECTION [75] Inventor: Eberhard Thamasett, Reutti,

Germany [73] Assignee: Wieland-Werke AG, Ulm, Germany [22] Filed: Apr. 6, 1973 21 Appl. No; 348,707

FOREIGN PATENTS OR APPLICATIONS Germany 72/84 Mar. 26, 1974 Primary ExaminerRichard J. Herbst Attorney, Agent, or Firm-Woodhams, Blanchard &

Flynn 57 ABSTRACT A device for the conical tapering of a continuously rotating elongated workpiece having a circular cross section which is rotatable about the longitudinal axis thereof. At least two tools which can be fed radially are simultaneously advanced in axial direction and are arranged in one plane at a right angle to the workpiece axis. Each of the tools consists of two nonmovably connected working surfaces which define an angle with the infeed direction of the tools. On both tools the working surface which is the leading surface into each of the tools in the direction of rotation of the workpiece is longer than the other working surface and same is at most so long that when the tools are completely moved forwardly against one another the shorter working surface of each tool abuts with its front or leading side the longer working surface of the respectively other tool.

3 Claims, 3 Drawing Figures 1 DEVICE FOR THE CONICAL TAPERING OF ELONGATED WORKPIECES HAVING A CIRCULAR CROSS SECTION The invention relates to a device for the conical tapering of a continuously rotating elongated workpiece having a circular cross section which is rotatable about the longitudinal axis. At least two tools which can be fed radially are alsosimultaneously advanced in the axial direction and are arranged in one plane at a right angle to the workpiece axis. Each of the tools consists of two nonmovably connected working surfaces which define an angle with the infeed direction of the tools.

Devices of this type are known from German Pat. No. 1 285 433. The working surfaces in these devices are equal in length as viewed in the direction of rotation of the workpiece, so that the geometrically greatest possible diameter condition can be achieved at which a reduction of the original workpiece diameter is possible if both tools are moved forwardly completely against one another. This geometrically greatest possible diameter condition depends on the angle which is defined between the working surface, which lies tangentially on the workpiece, and the infeed direction of the tool. In order to reach great values for the diameter conditions, this angle is supposed to be, if possible, larger than 45. On the other side, the force engaging points of the working surfaces on the workpiece are supposed to be equally spaced as much as possible over the periphery of the workpiece, which, however, especially requires an angle of 45 between each working surface and the infeed direction.

The basic purpose of the invention is to construct a device of the type mentioned above so that, in spite of maintaining the angle of 45 between the working surfaces and the infeed direction, the relationship between the original workpiece diameter and the smallest possible reduced diameter is increased.

Surprisingly this purpose of the invention can be attained in such a manner that on both tools the working surface which is in front or leads into the tool as viewed from the direction of rotation of the workpiece is longer than the other working'surface and same is at most so long that when the tools are completely moved forwardly against one another the shorter working surface of each tool abuts with its front or leading side the longer working surface of the respectively other tool.

Through this design of the working surfaces, the smallest diameter to which the workpiece can be reduced is not changed in comparison to the known embodiment having solely working surfaces which are equal in length. Contrary to this, the maximum original workpiece diameter which the workpiece may have prior to the reduction operation is unexpectedly enlarged. Thus, the maximum reduction condition is also correspondingly increased. This surprising success is probably due to the fact that the workpiece experiences a deformation of its cross-sectional surface or change in wall thickness during its reduction in diameter caused, for example, by a material accumulation which leads to a widening of the abutment surface between the workpiece and the working surfaces, which widening is effective mainly against the direction of rotation of the workpiece. This widened abutment surface may not reach the front edge of the working surface of both tools, which working surface is the front or leading one into the tool as viewed from the direction of rotation of the workpiece, otherwise, the front edge would be able to cut into the workpiece and tear it open. This is obviously prevented by the invention in that the front edge is advanced forwardly against the workpiece by the extension of the working surface which is the front or leading one into each tool and the workpiece thus has the possibility to build up the material accumulation before the front edge is reached.

Optimum conditions exist when the two shorter working surfaces have their maximum possible length abut the front or leading side straight on the longer working surface of the respectively other tool when the tools are completely moved forwardly against one another. These conditions can constructively be realized in the simplest manner in that on both tools the two working surfaces are each formed by the surface of a disk which is circular in cross section and both'disks are stationarily and nonmovably secured on a tool holder in such a manner that the axes of both disks lie in the plane which is at a right angle to the workpiece axis, whereby from the respective sloping of the line of intersection of this plane with the surface of each disk results the angle of the working surface with respect to the infeed direction of the tool and the disk which is in front or leads into each tool as viewed from the direction of rotation of the workpiece is thicker in direction of the disk axisthan the other disk. The respective thicker disk finds then room without any further measures on the frontor leading side besides the thinner disk of the respective other tool, when the two tools are put together to form the smallest possible reduction in diameter. Moreover such round disks can be manufactured with little expense very precisely in diameter and can'be secured in a correspondingly precise position onthe'tool holder so that the even support of the workpiece on the working'surfaces meets the high requirements of precision. The disks themselves do not need to be manufactured in different thicknesses. It is advantageous to manufacture all disks so that they are identical and then to make the arrangement so that the thicker diskconsists of a base member, which has the dimensions of the other disk, and washers, which washers are placed between the base member and the tool holder.

The technical forward step which has been achieved with the present invention consists substantially in that without changing the angle defined between the working surfaces and the infeed direction of the tools, the maximum possible reduction relationship can be increased, namely particularly by maintaining an angle of 45 at which an optimum support of the workpiece on the working surfaces exists. The extension of the working surface of both tools, which working surface is the front or leading one in the direction of rotation of the workpiece and which extension is only required for this purpose, can be realized with the help of the circular disks in a particular favorable manner.

The invention will be described more in detail hereinafter by reference to the exemplary embodiments in the drawings, in which:

FIG. 1 is a cross-sectional view taken along a line transverse of the workpiece axis of a device of the invention with an only schematically illustrated infeed mechanism for the tools,

FIG. 2 is a different embodiment of the device of FIG. 1, and

FIG. 3 is a further embodiment of a device of the invention.

The figures of the drawing illustrate schematically devices for the conical tapering of an elongated workpiece which in the exemplary embodiment is a tube 1. The two tools 2 move toward and away from each other in the direction of the arrows 3, which arrows indicate the infeed direction of the tools 2. The tools 2 are, for example, secured to a movable carriage 4 mounted on schematically illustrated rollers 5 which are guided on a support 6 movable in the longitudinai direction of the workpiece 1. The tools 2 are fed in the direction of the arrows 3 simultaneously with a continuous rotation of the workpiece 1 about its longitudinal axis, the direction of rotation of the workpiece 1 being indicated by the arrow7. The tools 2 are also simultaneously moved in an axial direction longitudinally of the workpiece 1 by means of the movable support 6. Each tool 2 has nonmovable working surfaces 8, 8 which define an angle a with the infeed direction 3 of the tools 2. In both tools 2, the working surface 8 which is the front one in direction of rotation 7 of the workpiece 1 is longer than the other working surface 8. The working surface 8 is at most just long enough so that when the tools 2 are completely moved forwardly or inwardly against one another,'the leading edge of the shorter working surface 8 of each tool 2 engages the longer working surface 8' of the respectively other tool, as is illustrated in the exemplary embodiments according to FIGS. 2 and 3. Compared with these exemplary embodiments, the respectively shorter working surface 8 is further shortened in the embodiment according to FIG. 1 in order to simplify the contour of the tools 2 which are of a platelike shape in the exemplary embodiment according to FIGS. 1 and 2, which, however, is connected with an impairment of the conditions which are at an optimum in FIG. 2 with respect to the maximum possible reduction conditions. In the exempIary embodiment of FIG. 3, these optimum conditions can be realized in a particularly simple manner by forming on both tools 2 the two working surfaces 8, 8' each by the surface of a disk 9, 9 which is circular in cross section. Both disks 9, 9' are fixedly secured to a tool holder 10 so that the axes of both disks 9, 9 lie in a plane which is at a right angle to the workpiece axis, which in FIG. 3 is the plane of the drawing. The disk 9 which is in front in the direction of rotation 7 of the workpiece I is all together thicker in direction of the disk axis than the respectively other disk 9. In the exemplary embodiment, the thicker disk 9' consists of a base member 11 having the same dimensions as the other disk 9 and washers 12 which are inserted between the base member 11 and the tool holder 10. The disks 9, 9' are inserted into pockets 14 of the tool holders 10 and are secured in position by means of screws 13.

The shorter working surface 8 on one of the tools is opposite the longer working surface 8 on the other of the tools. Furthermore the direction of rotation 7 of the workpiece 1 must be considered. If this direction of rotation is reversed with respect to the arrow which is illustrated in the drawing, then the sequence of the respectively longer and shorter working surface 8, 8' must also be reversed. In the sense of the direction of rotation 7 of the workpiece l, the longer workingsurface 8' must always lie in front of the shorter one 8. For example, the top most portion of the workpiece 1 in FIG. 3 will first contact the longer working surface 8' of the left tool holder 10 and, similarly, the bottom most portion of the workpiece l in FIG. 3 will first contact the working surface 8' of the right tool holder 10. Otherwise the front or leading edge 15 of the shorter working surface 8 will cut into the workpiece 1 and tear open the tube wall.

The device according to FIG. 3 has conically tapered soft tubes of AlZnMgCu having dimensions of 15.0 mm. in diameter and having a wall thickness of 0.8 mm. to a smallest diameter of 8 mm. during one cyclic operation of the tools. The cylindrical disks 9, 9 had a diameter of 20 mm., the two disks had a thickness of 9 mm. and 8 mm. respectively. The angle or between the working surfaces and the infeed direction was 45. Compared with this, in the case of two equally thick disks having a thickness of 8 mm. and without washers 12, only a greatest possible starting diameter of the tubes of 13 mm. was possible. The extension of the working surface 8 by 1 mm., which working surface is the front or leading one as explained above in the direction of rotation of the workpiece 1, resulted in an increase in the maximum possible original tube diameter of 2 mm.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A device for the conical tapering of continuously rotating elongated workpieces rotatable about the longitudinal axis thereof and having a circular cross section, said device being simultaneously advanced in the axial direction of said workpiece, at least two tools feedable radially inwardly and are arranged in one plane at a right angle to the workpiece axis, each of which tools comprises two non-movably connected working surfaces which define an angle with the infeed direction of the tools, comprising the improvement wherein a first working surface is the leading surface into each of the tools in the direction of rotation of the workpiece and is longer than the second working surface and the first working surface is at most so long that when the tools are completely moved forwardly against one another the second working surface in each tool abuts with its front or leading side the first working surface of the respectively second tool.

2. A device according to claim 1, wherein on both tools the two working surfaces are each formed by the surface of a disk which is circular in cross section and both disks are stationarily and nonmovably secured on a tool holder in such a manner that the axes of both disks lie in a plane which is at a right angle to the workpiece axis, whereby from the respective sloping of the 7 line of intersection of this plane with the surface of each disk results the angle of the working surface with respect to the infeed direction of the tool and the disk which is the leading one into the tool as viewed from the direction of rotation of the workpiece is thicker in direction of the disk axis than the other disk.

3. A device according to claim 2, wherein the thicker disk consists of a base member which has the dimensions of the other disk and washers which are placed between the base member and the tool holder. 

1. A device for the conical tapering of continuously rotating elongated workpieces rotatable about the longitudinal axis thereof and having a circular cross section, said device being simultaneously advanced in the axial direction of said workpiece, at least two tools feedable radially inwardly and are arranged in one plane at a right angle to the workpiece axis, each of which tools comprises two non-movably connected working surfaces which define an angle with the infeed direction of the tools, comprising the improvement wherein a first working surface is the leading surface into each of the tools in the direction of rotation of the workpiece and is longer than the second working surface and the first working surface is at most so long that when the tools are completely moved forwardly against one another the second working surface in each tool abuts with its front or leading side the first working surface of the respectively second tool.
 2. A device according to claim 1, wherein on both tools the two working surfaces are each formed by the surface of a disk which is circular in cross section and both disks are stationarily and nonmovably secured on a tool holder in such a manner that the axes of both disks lie in a plane which is at a right angle to the workpiece axis, whereby from the respective sloping of the line of intersection of this plane with the surface of each disk results the angle of the working surface with respect to the infeed direction of the tool and the disk which is the leading one into the tool as viewed from the direction of rotation of the workpiece is thicker in direction of the disk axis than the other disk.
 3. A device according to claim 2, wherein the thicker disk consists of a base member which has the dimensions of the other disk and washers which are placed between the base member and the tool holder. 